JP4243495B2

JP4243495B2 - Method for manufacturing photoelectric conversion device

Info

Publication number: JP4243495B2
Application number: JP2003040322A
Authority: JP
Inventors: 信菅原; 淳雄旗手; 晶子瀬戸口; 久雄有宗
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2003-02-18
Filing date: 2003-02-18
Publication date: 2009-03-25
Anticipated expiration: 2023-02-18
Also published as: JP2004253486A

Description

【０００１】
【発明の属する技術分野】
本発明は太陽光発電に使用される光電変換装置及びその製造方法に関し、特に結晶質半導体粒子を用いた光電変換装置及びその製造方法に関する。
【０００２】
【従来の技術】
省シリコン原料の低コストな次世代太陽電池の出現が強く望まれている。省資源に有利な粒形もしくは球形のシリコン結晶粒子を用いる従来の光電変換装置を図２に示す（例えば特許文献１参照）。この光電変換装置は、基板１上に低融点金属層８を形成し、この低融点金属層８上に半導体粒子３を配設し、この半導体粒子３上に第２導電型の非晶質半導体層４と透明導電層５を上記低融点金属層８との間に絶縁層２を介して形成する光電変換装置が開示されている。
【０００３】
また、図３に示すように、金属電極１上にアルミニウムペースト１０を形成し、このアルミニウムペースト１０上に半導体粒子３を配設し、この半導体粒子３上に第２導電型の微結晶半導体層９と透明電極層５を上記アルミニウムペースト１０との間に絶縁層２を介して形成する光電変換装置が開示されている（例えば、特許文献２参照）。
【０００４】
〔特許文献１〕
特許第２６４１８００号公報
〔特許文献２〕
特開平３−２２８３７９号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、図２に示す従来の光電変換装置では、半導体粒子３上の絶縁層２を研磨して半導体粒子３を露出させ、その露出させた表面に第２導電型の非晶質半導体層４を形成してＰＮ接合を形成する。そのためにＰＮ接合界面に研磨による物理的ダメージが残り、ＰＮ接合の品質が低下して変換効率が低下するとともに、このような研磨工程は生産性が悪いという問題点があった。
【０００６】
また、図３に示す従来の光電変換装置でも研磨により半導体粒子３を露出させた面にＰＮ接合を形成するために、ＰＮ接合の品質が低下して変換効率が低下するとともに、このような研磨工程は生産性が悪いという問題点があった。
【０００７】
本発明は上記従来技術における問題点に鑑みてなされたものであり、その目的は高い変換効率且つ高い生産性を有する光電変換装置の製造方法を提供することにある。
【０００８】
【課題を解決するための手段】
本発明に係る光電変換装置の製造方法によれば、一方の電極となる基板上に、第１導電型の結晶質半導体粒子を多数配設し、この結晶質半導体粒子上に第２導電型の半導体層を形成し、この結晶質半導体粒子間に絶縁物質を介在させて上部電極を形成する光電変換装置の製造方法において、前記第２導電型の半導体層をその層中の微量元素が低濃度から高濃度になるように濃度勾配をつけて形成した後に前記絶縁層を形成することを特徴とする。
【０００９】
上記光電変換装置の製造方法では、前記第２導電型の半導体層を形成した後に前記基板上の前記第２導電型の半導体層を除去することが好ましい。
【００１０】
上記光電変換装置の製造方法では、前記基板がアルミニウム又はアルミニウム合金であり、前記基板上の半導体層を除去する工程がフッ酸、塩酸、硫酸または燐酸によるエッチングであることが好ましい。
【００１６】
【発明の実施の形態】
以下、図面に基づいて本発明を詳細に説明する。
図１は本発明に係る光電変換装置の一実施形態を示す断面図であり、１は基板、２は絶縁層、３は第１導電型の結晶質半導体粒子、４は第２導電型の半導体層、５は上部電極層である。
【００１７】
基板１としては、金属、ガラス、セラミック及び樹脂等が用いられる。好ましくは、銀、アルミニウム、銅等の高反射金属である。基板１の反射率が大きいことで、基板１で光を反射させて粒状結晶シリコン３へより多くの光を導くことができ、変換効率が向上するために好ましい。また、基板１として絶縁体を用いる場合には、基板１の表面に下部電極となる導電層を形成する必要がある。この導電層は、高反射材料であることが好ましい。また、基板１はアルミニウム又はアルミニウム合金であることが好ましい。基板１がアルミニウム又はアルミニウム合金である場合、基板１上に形成した第２導電型の半導体層４をフッ酸、塩酸、硫酸または燐酸による処理により除去可能となるため好ましい。これは、アルミニウムまたはアルミニウム合金からなる基板１をエッチングすることで、基板１上に形成した第２導電型の半導体層４を基板１の表層ごと剥離することができるためと考えられる。また、基板１表面は粗面であることが好ましい。基板１表面が粗面でない場合、基板１上に形成した第２導電型の半導体層４を除去しにくいからである。
【００１８】
絶縁層２は、正極と負極の分離を行うために結晶質半導体粒子３間に充填する。絶縁層２としては、ガラス材料、樹脂材料、無機有機複合材料等である。絶縁層２は第２導電型の半導体層４を形成した後に形成する。第２導電型の半導体層４は結晶質半導体粒子３上にそれぞれ独立して形成されるだけであり、後述する上部電極層５で相互に接続される。絶縁物質２を形成する前にＰＮ接合を形成することにより、絶縁層２を除去する工程が不要となること、更に絶縁層２を除去することによる欠陥や絶縁層２による汚染が原因でＰＮ接合の品質を低下させることが無く、高い変換効率が実現できる。絶縁層２の波長４００ｎｍ〜１２００ｎｍの透過率は７０％以上であることが好ましい。透過率が７０％以下のとき、粒状結晶シリコンへ入射する光の量が減少して変換効率が低下するため好ましくない。
【００１９】
第１導電型の結晶質半導体粒子３は、シリコン、ゲルマニウム等からなるが、半導体３に添加してＰ型又はｎ型を呈するＢ、Ｐ、Ａｌ、Ａｓ、Ｓｂ等を含んでもよい。前記結晶質半導体粒子３は、気相成長法、アトマイズ法、直流プラズマ法等で形成可能であるが、非接触環境下に融液を落下させる融液落下法が好ましい。また、第１導電型の結晶質半導体粒子３はｐ型であることが好ましい。例えば、半導体材料に添加してｐ型を呈するＢ、Ａｌを１×１０^１４〜１０^１８ａｔｏｍｓ／ｃｍ^３程度添加したものである。
【００２０】
第２導電型の半導体層４は、プラズマＣＶＤ法、触媒ＣＶＤ法、スパッタリング法等で形成する。この結晶質半導体粒子３上のみに第２導電型の半導体層４を形成する。結晶質半導体粒子３上のみではなく、絶縁層２上にも第２導電型の半導体層４を形成するとき光吸収ロスが大きくなり、結晶質半導体粒子３へ入射する光が減少するため好ましくない。また、第２導電型の半導体層４を絶縁層２を形成する前に形成することが好ましい。第２導電型の半導体層４を絶縁層２を形成した後に形成するとｐｎ接合面積が絶縁層の形状によって決定されるため好ましくない。第２導電型の半導体層４で結晶質半導体粒子３表面を覆うことにより表面再結合を低減させ変換効率が向上するため好ましい。
【００２１】
また、第２導電型の半導体層４の微量元素は、濃度勾配を有する。微量元素の濃度は、結晶質半導体粒子３側で低く、膜厚方向に順次濃度が高く形成する。微量元素は、例えば、半導体材料に添加してｐ型又はｎ型を呈するＢ、Ｐ、Ａｌ、Ａｓ、Ｓｂの他、酸素、窒素、炭素、水素等である。第２導電型の半導体層４の微量元素濃度を結晶質半導体粒子３側で低く形成することにより、第２導電型の半導体層４を介して基板１へ流れるリーク電流の低減、結晶質半導体粒子３の表面再結合の低減、絶縁層２との密着性向上、上部電極膜５との密着性向上、上部電極膜５と半導体層４間の直列抵抗の低減に効果がある。特に、Ｂ、Ｐ、Ａｌ、Ａｓ、Ｓｂの濃度勾配は第２導電型の半導体層４を介して基板１へ流れるリーク電流の低減、結晶質半導体粒子３の表面再結合の低減、上部電極膜５と半導体層４間の直列抵抗の低減に効果が大きい。また、酸素、窒素、炭素、水素の濃度勾配は絶縁層２との密着性向上、上部電極膜５との密着性向上に効果が大きい。また、第２導電型の半導体層４の微量元素濃度は、例えば結晶質半導体粒子３側で５×１０^１５〜５×１０^１９ａｔｏｍｓ／ｃｍ^３程度であり、上部電極側で１×１０^１８〜５×１０^２１ａｔｏｍｓ／ｃｍ^３程度である。微量元素の制御方法として、半導体層４形成時に微量元素を含むガスを添加する方法、半導体層４形成後に微量元素を含む雰囲気下で加熱処理する方法等がある。また、前記第２導電型の半導体層４の微量元素の低濃度側は真性半導体層であることが望ましい。
【００２２】
第２導電型の半導体層４の膜厚は５ｎｍ以上１００ｎｍ以下であることが好ましい。第２導電型の半導体層４の膜厚が５ｎｍ未満のとき、第２導電型の半導体層４の膜が島状に形成され、半導体層４の被覆不良箇所が発生するため好ましくない。第２導電型の半導体層４の膜厚が６０ｎｍを超えるとき、第２導電型の半導体層４を通って下部電極にながれるリーク電流が大きくなり且つ第２導電型の半導体層４の光吸収が大きくなり、変換効率が低下するため好ましくない。また、半導体層４は膜厚分布を有することが好ましい。半導体粒子３の上部と下部で半導体層４が膜厚分布を有することが好ましい。下部の膜厚は上部の７０％未満であることが好ましい。更に好ましくは５０％未満である。下部の膜厚を薄くすることにより第２導電型の半導体層４を通って下部電極にながれるリーク電流が小さくなるため好ましい。また、結晶質半導体粒子３と第２導電型の半導体層の間に酸化層又は窒化層を形成することが望ましい。また、第２導電型の半導体層は非晶質、微結晶質、ナノ結晶質いずれであってもよい。
【００２３】
また、本発明は単一接合型の光電変換装置に限ったものではなく、複数の接合を有する光電変換装置においても同様の効果を呈する。複数の接合を有する光電変換装置として、例えば、ｐ型結晶半導体粒子上にｎ型微結晶質半導体層を形成し、その上に中間層を介してｐ型非晶質半導体層、Ｉ型非晶質半導体層、ｎ型非晶質半導体層を順次形成したタンデム型光電変換装置等であってもよい。
【００２４】
上部電極膜５は、酸化錫、酸化インジウム等をスパッタリング法等で形成する。膜厚及び屈折率を調整することにより反射防止効果を持たせることも可能である。更に、その上に銀又は銅ペーストを用いた適切なパターンで補助電極を形成してもよい。
【００２５】
【実施例】
次に、本発明の光電変換装置の具体例を説明する。
まず、アルミニウム基板１上に平均粒径２００μｍの粒状結晶ｐ型シリコン３を密に１層配設し、加熱して基板１と粒状結晶シリコン３を溶着させた。次に、ｎ型非晶質半導体層４をプラズマＣＶＤ法により基板温度２００℃で膜厚方向にリン濃度を変化させて４０ｎｍ成膜し、電気特性を評価した結果を表１にまとめる。次に、フェノール樹脂を粒状結晶シリコン間に充填させ２００℃に加熱焼成して絶縁層２を形成した。その上に酸化錫からなる上部電極膜５を１００ｎｍ形成して評価した。
【００２６】
【表１】

【００２７】
上記結果から分かるように、ｎ型半導体層４を絶縁層形成前に形成し、ｎ型半導体層が濃度勾配を有し、ｎ型半導体層４の結晶質半導体粒子側のリン濃度が低いとき変換効率が向上する。
【００２８】
次に、アルミニウム・シリコン合金基板１上に平均粒径５００μｍの粒状結晶ｐ型シリコン３を密に１層配設し、加熱して基板１と粒状結晶シリコン３を溶着させた。次に、ｎ型混晶質半導体層４をプラズマＣＶＤ法により基板温度１５０℃で膜厚方向に酸素濃度を変化させて３０ｎｍ成膜し、信頼性を評価した結果を表２にまとめる。次に、ポリイミド樹脂を粒状結晶シリコン間に充填させ２００℃に加熱焼成して絶縁層２を形成した。その上にＩＴＯからなる上部電極膜５を９０ｎｍ形成して評価した。信頼性の評価方法は、８０℃９０％ＲＨ環境で３０００時間放置した後の電気特性変化を測定評価した。
【００２９】
【表２】

【００３０】
上記結果から分かるように、ｎ型半導体層４を絶縁層形成前に形成し、第２導電型の半導体層が濃度勾配を有し、ｎ型半導体層４の結晶質半導体粒子側の酸素濃度が低いとき高い信頼性が実現する。
【００３１】
【発明の効果】
以上のように、本発明の光電変換装置の製造方法によれば、一方の電極となる基板上に、第１導電型の結晶質半導体粒子を多数配設し、この結晶質半導体粒子上に第２導電型の半導体層を形成し、この結晶質半導体粒子間に絶縁物質を介在させて上部電極を形成した光電変換装置において、上記第２導電型の半導体層を上記結晶質半導体粒子上のみに設けるとともに、この第２導電型の半導体層中の微量元素の濃度が上記結晶質半導体粒子側で低くなるように勾配を設けたことから、高い変換効率と高い信頼性が実現できる。
【図面の簡単な説明】
【図１】本発明の製造方法で製造された光電変換装置を示す断面図である。
【図２】従来の光電変換装置を示す断面図である。
【図３】従来の他の光電変換装置を示す断面図である。
【符号の説明】
１・・・・基板
２・・・・絶縁層
３・・・・第１導電型の結晶質半導体粒子
４・・・・第２導電型の半導体層
５・・・・保護膜
６・・・・透明導電層
７・・・・第２導電型の非晶質半導体層
８・・・・低融点金属層
９・・・・第２導電型の微結晶半導体層
１０・・・アルミニウムペースト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoelectric conversion device used for photovoltaic power generation and a manufacturing method thereof, and more particularly to a photoelectric conversion device using crystalline semiconductor particles and a manufacturing method thereof.
[0002]
[Prior art]
The advent of low-cost next-generation solar cells made from silicon-saving raw materials is strongly desired. FIG. 2 shows a conventional photoelectric conversion device using granular or spherical silicon crystal particles advantageous for resource saving (see, for example, Patent Document 1). In this photoelectric conversion device, a low melting point metal layer 8 is formed on a substrate 1, a semiconductor particle 3 is disposed on the low melting point metal layer 8, and a second conductivity type amorphous semiconductor is formed on the semiconductor particle 3. A photoelectric conversion device in which the layer 4 and the transparent conductive layer 5 are formed between the low melting point metal layer 8 and the insulating layer 2 is disclosed.
[0003]
Also, as shown in FIG. 3, an aluminum paste 10 is formed on the metal electrode 1, semiconductor particles 3 are disposed on the aluminum paste 10, and a second conductivity type microcrystalline semiconductor layer is formed on the semiconductor particles 3. A photoelectric conversion device is disclosed in which a transparent electrode layer 5 and a transparent electrode layer 5 are formed between an aluminum paste 10 and an insulating layer 2 (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent No. 2641800 [Patent Document 2]
Japanese Patent Laid-Open No. 3-228379
[Problems to be solved by the invention]
However, in the conventional photoelectric conversion device shown in FIG. 2, the insulating layer 2 on the semiconductor particle 3 is polished to expose the semiconductor particle 3, and the second conductive type amorphous semiconductor layer 4 is formed on the exposed surface. To form a PN junction. Therefore, physical damage due to polishing remains at the PN junction interface, the quality of the PN junction is lowered and conversion efficiency is lowered, and such a polishing process has a problem that productivity is poor.
[0006]
Further, in the conventional photoelectric conversion device shown in FIG. 3 as well, since the PN junction is formed on the surface where the semiconductor particles 3 are exposed by polishing, the quality of the PN junction is lowered and the conversion efficiency is lowered. The process had a problem that productivity was poor.
[0007]
The present invention has been made in view of the above problems in the prior art, and an object thereof is to provide a method for manufacturing a photoelectric conversion device having high conversion efficiency and high productivity.
[0008]
[Means for Solving the Problems]
According to the method for manufacturing a photoelectric conversion device according to the present invention, a large number of first-conductivity-type crystalline semiconductor particles are disposed on a substrate serving as one electrode, and a second-conductivity-type crystalline semiconductor particle is disposed on the crystalline semiconductor particles. In the method of manufacturing a photoelectric conversion device in which a semiconductor layer is formed and an upper electrode is formed by interposing an insulating substance between the crystalline semiconductor particles, the second conductive type semiconductor layer has a low concentration of trace elements in the layer. The insulating layer is formed after forming with a concentration gradient so that the concentration becomes high.
[0009]
In the method for manufacturing the photoelectric conversion device, it is preferable that the second conductive semiconductor layer on the substrate is removed after the second conductive semiconductor layer is formed.
[0010]
In the method for manufacturing a photoelectric conversion device, the substrate is preferably aluminum or an aluminum alloy, and the step of removing the semiconductor layer on the substrate is preferably etching using hydrofluoric acid, hydrochloric acid, sulfuric acid, or phosphoric acid.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a photoelectric conversion device according to the present invention, wherein 1 is a substrate, 2 is an insulating layer, 3 is a crystalline semiconductor particle of a first conductivity type, and 4 is a semiconductor of a second conductivity type. Layers 5 are upper electrode layers.
[0017]
As the substrate 1, metal, glass, ceramic, resin, or the like is used. A highly reflective metal such as silver, aluminum, or copper is preferable. Since the reflectance of the substrate 1 is large, light can be reflected by the substrate 1 and more light can be guided to the granular crystalline silicon 3, which is preferable because conversion efficiency is improved. When an insulator is used as the substrate 1, it is necessary to form a conductive layer serving as a lower electrode on the surface of the substrate 1. This conductive layer is preferably a highly reflective material. The substrate 1 is preferably made of aluminum or an aluminum alloy. When the substrate 1 is made of aluminum or an aluminum alloy, it is preferable because the second conductivity type semiconductor layer 4 formed on the substrate 1 can be removed by treatment with hydrofluoric acid, hydrochloric acid, sulfuric acid, or phosphoric acid. This is presumably because the semiconductor layer 4 of the second conductivity type formed on the substrate 1 can be peeled off together with the surface layer of the substrate 1 by etching the substrate 1 made of aluminum or an aluminum alloy. The surface of the substrate 1 is preferably a rough surface. This is because when the surface of the substrate 1 is not rough, it is difficult to remove the second conductivity type semiconductor layer 4 formed on the substrate 1.
[0018]
The insulating layer 2 is filled between the crystalline semiconductor particles 3 in order to separate the positive electrode and the negative electrode. The insulating layer 2 is a glass material, a resin material, an inorganic-organic composite material, or the like. The insulating layer 2 is formed after the second conductive type semiconductor layer 4 is formed. The semiconductor layer 4 of the second conductivity type is only formed independently on the crystalline semiconductor particles 3 and is connected to each other by an upper electrode layer 5 described later. Forming the PN junction before forming the insulating material 2 eliminates the need for the step of removing the insulating layer 2, and further causes a PN junction due to defects caused by the removal of the insulating layer 2 and contamination by the insulating layer 2. High conversion efficiency can be realized without degrading the quality of the image. The transmittance of the insulating layer 2 at a wavelength of 400 nm to 1200 nm is preferably 70% or more. A transmittance of 70% or less is not preferable because the amount of light incident on the granular crystalline silicon is reduced and conversion efficiency is lowered.
[0019]
The first conductive type crystalline semiconductor particles 3 are made of silicon, germanium, or the like, but may be added to the semiconductor 3 to include B, P, Al, As, Sb, or the like exhibiting P-type or n-type. The crystalline semiconductor particles 3 can be formed by a vapor phase growth method, an atomization method, a direct current plasma method, or the like, but a melt dropping method in which the melt is dropped in a non-contact environment is preferable. The first conductive type crystalline semiconductor particles 3 are preferably p-type. For example, B and Al, which are added to a semiconductor material and exhibit p-type, are added by about 1 × 10 ¹⁴ to 10 ¹⁸ atoms / cm ³ .
[0020]
The second conductivity type semiconductor layer 4 is formed by plasma CVD, catalytic CVD, sputtering, or the like. A second conductivity type semiconductor layer 4 is formed only on the crystalline semiconductor particles 3. When the second conductivity type semiconductor layer 4 is formed not only on the crystalline semiconductor particles 3 but also on the insulating layer 2, the light absorption loss increases, and the light incident on the crystalline semiconductor particles 3 decreases, which is not preferable. . In addition, it is preferable to form the second conductivity type semiconductor layer 4 before forming the insulating layer 2. Forming the second conductivity type semiconductor layer 4 after forming the insulating layer 2 is not preferable because the pn junction area is determined by the shape of the insulating layer. Covering the surface of the crystalline semiconductor particles 3 with the semiconductor layer 4 of the second conductivity type is preferable because surface recombination is reduced and conversion efficiency is improved.
[0021]
The trace elements in the second conductivity type semiconductor layer 4 have a concentration gradient. The concentration of the trace element is low on the crystalline semiconductor particle 3 side, and the concentration is gradually increased in the film thickness direction. The trace element is, for example, oxygen, nitrogen, carbon, hydrogen, or the like in addition to B, P, Al, As, Sb which is added to the semiconductor material and exhibits p-type or n-type. By forming the trace element concentration of the second conductivity type semiconductor layer 4 low on the crystalline semiconductor particle 3 side, the leakage current flowing to the substrate 1 through the second conductivity type semiconductor layer 4 is reduced, and the crystalline semiconductor particles 3 is effective in reducing the surface recombination of 3, improving the adhesion with the insulating layer 2, improving the adhesion with the upper electrode film 5, and reducing the series resistance between the upper electrode film 5 and the semiconductor layer 4. In particular, the concentration gradient of B, P, Al, As, and Sb is such that the leakage current flowing to the substrate 1 through the second conductivity type semiconductor layer 4 is reduced, the surface recombination of the crystalline semiconductor particles 3 is reduced, the upper electrode film Greatly reduces the series resistance between the semiconductor layer 4 and the semiconductor layer 4. In addition, the concentration gradient of oxygen, nitrogen, carbon, and hydrogen is highly effective in improving the adhesion with the insulating layer 2 and the adhesion with the upper electrode film 5. The trace element concentration of the second conductivity type semiconductor layer 4 is, for example, about 5 × 10 ^{15 to} 5 × 10 ¹⁹ atoms / cm ³ on the crystalline semiconductor particle 3 side, and 1 × 10 ¹⁸ to 5 × 10 ¹⁸ atoms / cm ³ on the upper electrode side. It is about 5 × 10 ²¹ atoms / cm ³ . As a control method of the trace element, there are a method of adding a gas containing a trace element when forming the semiconductor layer 4, a method of performing a heat treatment in an atmosphere containing the trace element after forming the semiconductor layer 4, and the like. Further, it is preferable that the low concentration side of the trace element in the second conductivity type semiconductor layer 4 is an intrinsic semiconductor layer.
[0022]
The film thickness of the second conductivity type semiconductor layer 4 is preferably 5 nm or more and 100 nm or less. When the film thickness of the second conductivity type semiconductor layer 4 is less than 5 nm, the film of the second conductivity type semiconductor layer 4 is formed in an island shape, and a poorly covered portion of the semiconductor layer 4 is generated. When the film thickness of the second conductivity type semiconductor layer 4 exceeds 60 nm, the leakage current flowing to the lower electrode through the second conductivity type semiconductor layer 4 increases, and the light absorption of the second conductivity type semiconductor layer 4 increases. This is not preferable because it increases and the conversion efficiency decreases. The semiconductor layer 4 preferably has a film thickness distribution. It is preferable that the semiconductor layer 4 has a film thickness distribution above and below the semiconductor particles 3. The film thickness of the lower part is preferably less than 70% of the upper part. More preferably, it is less than 50%. It is preferable to reduce the thickness of the lower portion because the leakage current flowing to the lower electrode through the second conductivity type semiconductor layer 4 is reduced. Further, it is desirable to form an oxide layer or a nitride layer between the crystalline semiconductor particles 3 and the second conductivity type semiconductor layer. The second conductivity type semiconductor layer may be amorphous, microcrystalline, or nanocrystalline.
[0023]
Further, the present invention is not limited to the single junction type photoelectric conversion device, and the same effect can be obtained in a photoelectric conversion device having a plurality of junctions. As a photoelectric conversion device having a plurality of junctions, for example, an n-type microcrystalline semiconductor layer is formed on a p-type crystal semiconductor particle, and a p-type amorphous semiconductor layer or an I-type amorphous is formed thereon via an intermediate layer. A tandem photoelectric conversion device or the like in which a crystalline semiconductor layer and an n-type amorphous semiconductor layer are sequentially formed may be used.
[0024]
The upper electrode film 5 is formed of tin oxide, indium oxide, or the like by a sputtering method or the like. It is also possible to provide an antireflection effect by adjusting the film thickness and refractive index. Furthermore, you may form an auxiliary electrode in the suitable pattern which used silver or copper paste on it.
[0025]
【Example】
Next, specific examples of the photoelectric conversion device of the present invention will be described.
First, one layer of granular crystal p-type silicon 3 having an average particle diameter of 200 μm was densely arranged on the aluminum substrate 1 and heated to weld the substrate 1 and the granular crystal silicon 3. Next, the n-type amorphous semiconductor layer 4 is formed to a thickness of 40 nm by changing the phosphorus concentration in the film thickness direction at a substrate temperature of 200 ° C. by plasma CVD, and the results of evaluating the electrical characteristics are summarized in Table 1. Next, a phenol resin was filled between the granular crystalline silicon, and heated and fired at 200 ° C. to form the insulating layer 2. An upper electrode film 5 made of tin oxide was formed to 100 nm thereon and evaluated.
[0026]
[Table 1]

[0027]
As can be seen from the above results, conversion is performed when the n-type semiconductor layer 4 is formed before the insulating layer is formed, the n-type semiconductor layer has a concentration gradient, and the phosphorus concentration on the crystalline semiconductor particle side of the n-type semiconductor layer 4 is low. Efficiency is improved.
[0028]
Next, one layer of granular crystalline p-type silicon 3 having an average particle diameter of 500 μm was densely disposed on the aluminum / silicon alloy substrate 1 and heated to weld the substrate 1 and the granular crystalline silicon 3 together. Next, the n-type mixed crystal semiconductor layer 4 is formed to a thickness of 30 nm by changing the oxygen concentration in the film thickness direction at a substrate temperature of 150 ° C. by the plasma CVD method. Next, the insulating layer 2 was formed by filling the polyimide resin between the granular crystalline silicon and heating and baking at 200 ° C. An upper electrode film 5 made of ITO was formed to 90 nm thereon and evaluated. As a reliability evaluation method, a change in electrical characteristics after being allowed to stand for 3000 hours in an environment of 80 ° C. and 90% RH was measured and evaluated.
[0029]
[Table 2]

[0030]
As can be seen from the above results, the n-type semiconductor layer 4 is formed before forming the insulating layer, the second conductivity type semiconductor layer has a concentration gradient, and the oxygen concentration on the crystalline semiconductor particle side of the n-type semiconductor layer 4 is High reliability is achieved when low.
[0031]
【The invention's effect】
As described above, according to the method for manufacturing a photoelectric conversion device of the present invention, a large number of first-conductivity-type crystalline semiconductor particles are arranged on a substrate serving as one electrode, and the first conductive-type crystalline semiconductor particles are formed on the crystalline semiconductor particles. In a photoelectric conversion device in which a two-conductivity type semiconductor layer is formed and an upper electrode is formed by interposing an insulating material between the crystalline semiconductor particles, the second-conductivity-type semiconductor layer is formed only on the crystalline semiconductor particles. In addition, since the gradient is provided so that the concentration of the trace element in the second conductivity type semiconductor layer becomes lower on the crystalline semiconductor particle side, high conversion efficiency and high reliability can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a photoelectric conversion device manufactured by a manufacturing method of the present invention.
FIG. 2 is a cross-sectional view showing a conventional photoelectric conversion device.
FIG. 3 is a cross-sectional view showing another conventional photoelectric conversion device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ...... substrate 2 ... insulating layer 3 ... 1st conductivity type crystalline semiconductor particle 4 ... 2nd conductivity type semiconductor layer 5 ... protective film 6 ... -Transparent conductive layer 7-second conductive type amorphous semiconductor layer 8-low melting point metal layer 9-second conductive type microcrystalline semiconductor layer 10-aluminum paste

Claims

A large number of first-conductivity-type crystalline semiconductor particles are disposed on a substrate serving as one electrode, a second-conductivity-type semiconductor layer is formed on the crystalline semiconductor particles, and insulation is provided between the crystalline semiconductor particles. In the method of manufacturing a photoelectric conversion device that forms an upper electrode with a substance interposed,
A method of manufacturing a photoelectric conversion device, comprising: forming the insulating layer after forming the second conductivity type semiconductor layer with a concentration gradient so that a trace element in the layer is changed from a low concentration to a high concentration. .

Process for producing a photovoltaic device according to claim 1, wherein the removing the semiconductor layer of the second conductivity type of the substrate after forming a semiconductor layer of the second conductivity type.

3. The method of manufacturing a photoelectric conversion device according to claim 2, wherein the substrate is aluminum or an aluminum alloy, and the step of removing the semiconductor layer on the substrate is etching with hydrofluoric acid, hydrochloric acid, sulfuric acid, or phosphoric acid.